Effect of nanoscale silica fume and carbon nanotube on damping capacity of cement-based composite

Nanoscale Ultrafine Silica Fume (USF) or/and Multi-Walled Carbon Nanotube (MWCNT) were incorporated into cement matrix to fabricate 3 groups nanocomposites, with associated the reference (Plain/C). The critical damping ratios (ζ) and flexural strengths (σ) of these composites were investigated with free attenuation method in an elastic system, half-power bandwidth technique and subsequently three-point bending testing method, respectively, to evaluate the effect of USF or/and MWCNT additives on the damping and mechanical properties of cement matrix. Relative to the reference, the infilling and pozzolan effect of USF additive has positive influence on the enhancement of the σ of matrix, yet somewhat negative effect on that of ζ. The dislocation, viscous deformation effects of hollow nanotubes render the nanocomposite good damping behavior, yet the formation of defect and porosity with bad dispersion of MWCNT may jeopardize the enhancement of the σ. There are dual positive effects on the ζ and σ of the nanocomposite when with combinatory incorporation of USF and MWCNT, microstructure reveals there exist good cross linkages between USF, MWCNT and cement matrix, and the enhancement amplitude of the ζ and σ can increase by 30.21%, 24.13%, relative to the reference, respectively.